The invention concerns a milling machine to work ground surfaces, in particular pavements, as well as a process to dispose of dusts and vapors developing during the milling operation on a milling machine.
Such milling machines are self-propelled and are also referred to as road milling machines.
A front-loading milling machine in accordance is known from DE 102 23 819 A1. The known road milling machines show a self-propelled chassis with a travel drive unit consisting of several wheel units or several crawler track units. The chassis carries a machine frame in which a milling drum is supported transversely to the direction of travel. To achieve the completest possible removal of the milled material, the milling drum is generally enclosed by a housing, the wall of which pointing in the direction of travel is designed as a covering blade with an opening for the milled material. The material processed by the milling drum is accepted by a first transport conveyor, which transfers the processed material at the forward end of the milling machine onto a discharge conveyor, which can be tilted and slewed laterally for transport onto a loading space of a truck.
It is already known from DE 102 23 819 A1 and EP 0 971 075 A1 to provide the transport conveyors of a road milling machine with a hood in order to suck off and dispose of the dust developing at the milling drum and beneath the hood of the transport conveyors by means of a ventilator and, where appropriate, a cyclone.
In EP 0 971 075 A1, it is proposed to suck off the dust against the direction of the material transport and to dispose of the dust by means of a ventilator and a cyclone at the rear end of the road milling machine. Here, it is of disadvantage that an extraction by suction at the transport conveyors takes place against the direction of transport. The dust-laden air is thereby sucked off towards the rear in the direction of travel and against the actual direction of the material transport, thus requiring a considerable additional expenditure for the equipment of the machine and a distinctly higher ventilator output. The particles separated by means of the ventilator and a downstream cyclone are dropped on the ground surface, thereby contaminating again the ground surface just milled. The cyclone dust separator provided at the rear end can separate only the coarser particles but not the respirable fine dusts, so that the arrangement of the air outlet at the rear end of the road milling machine is arranged too close to the operator's platform. In this way, the dusts and vapors are blown off at the rear end of the milling machine close to the operator's platform. In addition, the ventilator transports the dust-laden air so that high wear and tear leads to a short service life of the ventilator.
From DE 102 23 819 A1, it is therefore known to divide the channel formed by the hoods on the transport devices and to suck off the air polluted during milling in the direction of the material transport. This provides the advantage that the dusts and vapors are disposed of at a position located considerably farther away from the operator's platform and dust can only develop during the disposal onto the truck, where the development of dust is unavoidable anyway, and not additionally behind the road milling machine close to the operator's platform.
According to the prior art, the suction device shows an axial-flow fan arranged in a suction channel which, due to the high exposure to dusts and sharp-edged particles, is subject to heavy wear and tear, which ultimately leads to a reduced air output and the development of bearing damages. The fan blades of the axial-flow fan are heavily worn and damaged due to the impact and the deflection of the particles being conveyed at high speed. When larger particles and smaller stones are sucked in, other parts of the ventilator are also damaged mechanically, which in case of a damage to the fan blades frequently results in the occurrence of unbalances leading to bearing damages in continued operation. In case of repair, it is of disadvantage that the ventilator is arranged at a position which is difficult to access and a repair therefore leads to a major break in operation. Finally, due to the transport of the dusts and the sharp-edged particles, the ventilator must be designed in such a way that the clearance between the fan blades and the walls of the ventilator is larger so that the air output and the efficiency of such a ventilator for dust-laden and particle-laden air is lower.
A further disadvantage is that although the dusts are blown off at a distant position in relation to the operator's platform, they are still blown off into the environment so that a pollution of the workplace with dusts and vapors in the vicinity of the operator's platform, even if reduced, still exists.
Starting from this prior art, the task of the invention consists in creating a milling machine of the aforementioned type, as well as a process to dispose of dusts and vapors by means of which dusts and vapors developing during the milling operation and during the transport operation, in particular the respirable dusts, can be sucked off and disposed of with little mechanical expenditure and with higher effectiveness, and the service life of the suction device can be extended considerably at the same time.